9 02/18 Method D. Excavate and replace soil disturbed and weakened by the contractor’s operations or soils permitted to soften from exposure to weather, with bedding material and compact with a plate-type vibratory compactor. The minimum burial depth shall be a 30" cover over the pipe casing. Lesser depths could result in undesirable ground surface temperatures. TRENCH WIDTHS: The width of the trench at the top of the pipe should be held to the minimum required for efficient and proper installation. The reason for this is to keep the earth load on the pipe as small as possible, since, in general, the wider the trench at the top of the pipe, the greater the load on the pipe. Note that an increase on trench width above the top of the pipe, by sloping the sides or digging a wider offset trench, does not affect the earth load on the pipe. On the other hand, a trench that is too narrow will make assembly difficult and may reduce the rate and quality of installation. In addition, lack of ample room will limit the capability to properly backfill and tamp around the pipe. Although each job or portion of a job must be considered on an individual basis, as a rule, the following minimum trench widths at the top of the pipe are recommended: Minimum: One foot greater than the outside diameter of the casing. Where two or more pipes are in the same trench, use the distance between outside casing of the outside pipes plus one foot. Maximum: Use above method for minimum plus two feet. PLACING PIPE IN THE TRENCH: The Super Weld-Tite pipe shall be mechanically passed into the trench. The latest state and federal safety regulations should be understood and observed. If slings are necessary use only canvas straps, no cable or chain slings shall be used. BEDDING: The pipe should be bedded in accordance with basic good practices that apply to all buried pressure pipelines. WELDING: End covers should remain in place until welding operations are ready to begin. System sections including fittings and loops should first be laid out and aligned. Welding procedures shall be in accordance with contract specifications, ANSI B31.1 and good welding practices. TESTING: All carrier pipe joints shall be tested in accordance with the contract specifications before applying field joints. If no test is specified, it should consist of a hydrostatic test of 150 psi or 1 1/2 times working pressure, which ever is greater, for a period of two hours.